A spokesman for the Elysee Palace, the president's official residence, told Sky News the "rumour" was "not true" and said it was not preparing to issue a statement.

Patrice de Beer, former editor of French newspaper Le Monde, told Sky News he believes Mr Hollande announced the news to try to draw a line under the scandal.

Closer magazine published a story about Mr Hollande's love life

He said: "He wants to show there is a difference between his private life and his public life, which would probably mean that there shouldn't be any more first ladies in the future.

"And if he has a partner she won't be attending official functions, she won't have an office or bodyguards, she won't be part of official visits. Things have dragged on far too long."

Earlier this month, Mr Hollande admitted he was going through a "painful time" in his personal life after a French gossip magazine printed photos it claimed showed him spending a night with 41-year-old actress Julie Gayet.

Closer has since removed the report from its website, although it did not order copies of the publication to be pulled from news-stands.

Ms Gayet is suing the magazine for €50,000 (£41,650) in damages and €4,000 (£3,330) in legal costs, claiming it breached French privacy rules.

Mr Hollande threatened to sue over claims he had an affair with Julie Gayet

Mr Hollande, who has himself threatened legal action over the pictures, said he was "totally indignant" about the story, which he claimed threatened the principle of "respect for private life and people's dignity".

Although the president is not married to Ms Trierweiler, they were long-term partners.

She assumed the role of First Lady after Mr Hollande's election in 2012. It is not clear whether she remains First Lady following their announced separation.

Ms Trierweiler, 48, was admitted to hospital on January 10 with depression after the allegations about Mr Hollande's private life were published, and was released only last weekend.

She is due to fly to Mumbai in India on Sunday for a charity trip organised by Action Against Hunger, in what will be her first public appearance since the scandal broke.

Mr Hollande announced his separation from Segolene Royal, a senior member of his Socialist party and a presidential candidate in 2007, just after she lost the election to Nicolas Sarkozy.